Direct-current transformer



A. F. NYESBIL DIRECT CURRENT TRANSFORMER. `APPLICATION FILED MAR. 9| |921.

Patented Julyy 4, 1922.

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INVENTOR I f/l/Es/r amalfi/f WITNES SES I A. F. NESBIT.

DIRECT CURRENT TBANSFORMER.

APPLICATION mm MAB. 9, 192|.

v Patented July 4, 1922.

5 SHEETS-SHEET 2.

lNVEN-FOR I q F/VEsB/T k* @my A. F. NESBIT.

DIRECT CURRENT TRANSFOHMER.

APPLICATION FILED MAR. 9, 1921.

1,42 1 ,538 Patented July 4, 1922 5 SHEETS-SHEET 3.

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DIRECT CURRENT TRANsFonMfR. 1,421,538.

APPLICATION FILED MAE. 9, 1921.

Patented July 4, 1922.

5 SHEETS-SHEET 4.

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WITNESSEIS Z INVENTOR .q LY i 7 4 ,4 1111 A. F. NESBIT` DIRECT CURRENT TRRRSFORMER.

APPLICATION FILED MAR. 9, 192i.

Patented J uly 4, 1922.

5 SHEETS-SHEET 5- grouping JPiirlaziai OFFICE.

ARTHUR F. Nnsnrr, or WILKINSBURG, PENNSYLVANIA.

DIRECT- CURRENT TBANSFOBMEB:

' y To all wlwm it may concern.'

Be. it known that, I, ARTHUR F. Nnsnrr,

a citizen of the United States, and residentw 1 of VVilkinsburg in the county of Allegheny and State of lennsylvania, have invented certain new and useful Improvements in Direct-Current Transformers, of which the following is a specification.

My invention relates to 4direct current transformers of the class described and claimed in my co-pending application, Serial Number 164,430, filed April 25, 1917, Patent No. 1,371,994` March *15, 1921, and relates particularly to meansjfor securing the same phase of currentsin the primary coils of both ,the rmain and commtating elds. The principal object of this invention is to provide means for securing exact phase coincidence of currents inthe main and commutating primaryfield coils of my direct currentA transformer y connecting said coils in series with each other.

Referrin now to the drawings, forming part of this specification, Figure 1 is an elevation, partly in section and partly diagrammatic, showing a high potential, direct current, vertical transformer, e. a transformer having an axially vertical commutator shaft) constructed and arranged in accordance with my invention.

Figure 2 is a diagrammatic plan, o n a somewhat larger Scale (with the commutating field core and its windings omitted for the vsake of clearness). showing a preferred of the series of high "oltage coils on the ocked rotor.A and showing the conneetions betweenA the rotor coils and the commutator, on the commutator shaft in the particular construction illustrated in Figure 1.

Figure 3 is4 asectional elevation of .the cores and the windings or coils of the stator and rotor cores (shown in the preceding Figures.) and the commutating field emes the section being taken on *the line III-III of Figure 2.

Figure 4 is a diagrammatic plan` similar to that of Figure 2, showing the commutating field cores and the windings and connections to the windings on the axially adjustable primary commutating field core.

Figure is a plan showing details in the construction and arrangement of the slip rings and commutator segments and leads therefor as mounted on the commutator l.central and axially a cores B and .C isa rotar commutator shaft shaf and shown diagrammati'cally in Figure Figure 6 is a diagrammatic view of the' primary coils of the main andcomlmutating elds of the transformer showing the series circuitconnections used to secure the same phase of currents in the two sets of coils.

In the accompanying specification,- Vdue to the fact that the apparatus to be described is similar in structure to an induction motor the terms stator and rotor cores and coils;g respectively, are employed to designate the parts of the apparatus, which ,function 'similar to the henomena present in the operation of Van induction motor. However, since the part of this a paratus corresponding to the rotor core an" coil of an induction motor is at all times locked or stationary, the term rotor is ualified by referring to, said part as a loc ed rotor.

In the accompanying drawings the letter A designates the primary 1 or stator core and B the secondary or lockedvrotor core, of the annular, integrated structure forming these cores. By inte rated, as used herein, is meant a laminate structure having each lamina transversely divided into a series of segf ents and each segment forming part of t e core A and also part of the core B. WVhen constructed as shown, the cores have windings thereon forming twelve primary or stator coils al, a2, a?, a4, a", a, a', a", a, al", a, and au, and equal number of secondary or locked rotor coils b1, b2. b3, b, by., be br, be, be, blo, bi1, and biz' Mounted above and in axialA alinement with the stator and rotor cores are the commutating field cores C and C of my improved transformer. The angularly adjustable primary field core C has windings thereon forming its coils c1, c2, c3, c, c5, c, c?. c, cg, c, c1?, and cl2. The stationary secondary commutating field core C1 is embraced or encircled b the windings forming the coils b1, b2, 3, etc., of the locked rotor B (as is shown in Figures 1, 2 and 3).

Extending verticall through theaxially lined openings in the D and positioned on this shaft adjacent to its upper end, is a segmental commutating group or commutator E (Figures 2 and 5) and cooperating group of slip rings F, to which the segments of the commutator E are permanently connected electrically. The

A specincauun of Lettersiatent. Patented July 4, hwg; Y Application led March 9,1921. Serial No. 450,988.

lower end of the shaft D is connected to the armature shaft of a synchronous motor G by which the shaft D is rotated. 4This motor, as shown, is positioned below the oil tank or container H in which the stator A, locked rotor B, and commutating field cores' C and C are positioned so asto be submerged in the oil, It will be obvious, however, that the motor (i maybe supported above the tank H and be connected to the opposite end of the shaft D and also that the shaft D and its driving motor G may be located at a distance from the cores and coils of my improved apparatus. y,

The tank H is secured on a support 2 which is fixed on a suitable foundation and the cores A, B, are supported within the tank on a series of radial supports 3. The tank, which is cylindrical in cross section. is filled with oil to about the level indicated by the b'roken line 4, tokeep the stator A and rotor B immersed in the oil and provide for effective insulation of the stator and rotor, and the tank has a tight cover or lid 5 on its `upper end.

Suitable supports 6 are provided above or on top of the locked rotor ,core B "upon which the stationary or secondary core C1 of the commutating field core is positioned, and similar supports 7 above or on top of the stationary stator core provide means for supporting the angularly adjustable, axiall movable primary commutatlng field core and -series of windings forming its coils c, C". 6^. etc.

The primary commutating field core C is arranged to turn angularly relative to the stator and locked rotor cores A and B and the coils a1, (1.2, eter. and b1, b". etc.. thereon., this field core C turning about the vertical axis of the stator and locked rotor when being adjusted relative thereto and a suitable manually operated adjusting mechanism being provided for turning the comniutating field core C and for locking ,the core C in adjusted position (see Figure 1).

As shown,. the adjusting mechanism comprises a se menta-l gear or curved rack 8 secured on t e peripheryof the core C 4and having teeth in'mesh with those of the pinion 9 on one end -of the vertical shaft l0. The shaft is rotatably secured in the bracket bearings 11 and 12, which are fastened to the vertical wall of the tank H, and extends upwardly to or above the oil level 4 in the tank. The upper end of the shaft 1Q is provided with a worm wheel 13 which meshes with the worm 14 on one end of the horizontal shaft 15'. this shaft also being rotatably mounted in the upper bracket bearing 12. The shaft 15 extends through a stuffing box and gland on the side wall of the tank H and is provided on its outer end with a hand wheel 16 for turning the shafts 10 and 15 to adjust the primary commutating field core C and its' coils e angularly with respect to` As the adjustable commutating The rotary commutator shaft D, whieh'is l shown centered on the vertical axis of the annulus forming the cores A and B for thestator and locked rotor, (and the axis of the tank H), extends through a tube-"17 in the tank H and is provided, adjacent to its upper'end, with the commutator or segmental commutator group E and co-operating group 4F of twelve slip rings. f1, far, r; f2, f, ff.

f5, f", f1, f, and f. The tube 1711s as- -1 tened. by a flange 18 on its'lower end tothe bottom of the tank H to form an oil tight joint therebetween and a flange l19 on its upper end is secured to the cover or lid of the tank to rigidly fasten the tube in-upright p)osition within the tank. `The vertical shaft` is rotatably mounted in bearings 20, 21, whiclrare secured to the ends of the tan'k H, and a third bearing 22, on the spider 23 `is provided for the upper end of the shaft D. The spider 23'is secured in Yposition on the upper ends of vertical postsjZ-lr'which are fastened to the ulpper end of the tank D.

As shown` igures ,1, 2, and 3) the laminated. annular structure forming the integrated cores A and B is provided with a series of twelve rectangular or substantiall rectangular openings or gaps 25, throug which extend the windings forming the coils al; a?, as. etc., of the stator-A and coils L1, b,

b, etc., of the locked rotor B, when these coils are assembled in operative position on the cores. To facilitate assembling the parts forming the integratedy or unitarycores A and B, each lamina should be slitted and in buifldinlg up thelaminated structurethe slits ,in the a minae should be staggered to form overlapping joir/its. Such expedient being old and well kngwn in making laminated cores, need not bly/further described.

A The primary ei; stator circuit as shown, has a series of twelve polyp-hase windings a. fr etc.,` these coils preferably being connected in Y oinstar and the groups of coils having terniinalsm, m2, and ma, (see I Figure 2). The Secondary or locked rotor circuit has a series of twelve polypha se windings or-coils b1, b2, b, b, b5, b, b', b, b", b1", b, and b, which are'. connected in closed series as in a closed coil Gramm@ ring armature,

the series of coil b, b2, etc.. being properly insulated against the potential to be carried thereby.

Positioned immediately above the primary or stator 'core A and its coils a1, a2, etc., so as to be adjustable angularly relative to the coils on the core A, is the primary commutating field core C and its series of twelve windings or coils c1, c2, c3, 0, c2, c, c2, e", c", el, c, and cl2, which are also connected in Y or in star, and the roups of coils having terminals nl, n2, n2 (Figure 4) and immediatel above the secondary or locked rotor core ld is the secondary or stationary core C1, of the commutating field core, this core C1,being embraced or encircled by the wind ings forming the coils b1, b2,-etc of'the locked rotor core B (Figures 1, 2, and 4).

The terminals nl, n2, and n2 of the three groups of coils forming the primary commutating circuit, however, are not located directly above the similar points m1, m2, and m2, on the main primary circuit, but are displaced forward or backward with reference to them. This will represent a maximum possible magnetic dis lacement of approximately 90 degrees Tie magnetic flux produced by the windings c1, c2, c3, etc., will lag or lead according to the extent of adjustment with reference to the main primary magnetic flux.

The terminals of each coil of the electrically adjacent locked rotor coils b2 and b2, b2 and b2, b2 Iand b4, D* and b5, o and b, b'and b2, b2 and b2, b2 and b, b. and b1, b1 and b, b and b, 612 and b are connected together and have a common lead fr, ft2, h3, la, ai, lr, fr, is, h, le, 1111,.

or k12 and these leads` as shown are connected each to its individual ring il, i2, i2, if, i5, i, il, if", 2, il", i, and 12. The group of bus rings il, 112,1etc.. which encircles the shaft D and tube 17. is 'located within thetank H s0 as to' be immersed in the oil in this tank. Each of the rings i,'*z'.2,`etc., has a lead j, j2, js, j, j, j, jj, j", jl". jH'and j, which extends upwardly through an insulated opening in the tank cover or lid 5 and is connected by a carbon brush 'l, lf2, k2, c, fc5, lc, k2, k2, lc, k12, fr, and k12, to 'one of the slip rings f2, f2,

` f2, etc., in the group F of slip rings fastened on and rotating with the commutator shaft D.

Obviously the rings 1'. and leads j ma be omitted, in such case the leads k exten ing to the brushes le for the slip rings f.

The slip rings f1, f2, etc., are permanently connected electrically by leads Z1, Z2, Z2, etc., one to each of the commutator segments e1, 92,62, etc., forming the commutator E on the rotary commutator shaft D `adjacent to the' slip rings. (See Figure 5).

The commutator segments el, e2, e2, etc., are insulated from the shaft rD and from each other in any' of the various known ways and this insulation may conveniently be utilized to support and insulate theleads Z1, Z2. etc. The necessary number of leakage rings Q6 will lie-provided at the. ends of the group F ofy slip rings and on each side of the commutator F, and preferably 'a leakage ring 26a will be supplied on the commutator shaft D between the adjacent slip rings f1, f2, etc., as shown in Figure 5.

By splitting up the primary windings into a plurality or groups of coils, instead of one group for each phase as shown and described in connection with the apparatus of Figures 1, 2, and 3, a multiplicity of rotary fields will be obtained, instead of a single two pole rotary field, this having the effect of decreasing the secondary voltage and increasing the current carrying capacity of the locked. rotor or secondary circuit, by permitting the parallel grouping of the secondary coils.

The brush I on the commutato-r E is connected to the negative lead K and the brush J for the positive terminal is connected to Vthe lead L, these leads K, L, extending to the apparatus utilizingA the high potential unidirectional current generated by my improved apparatus. y The windings forming the primary or stator coils a, a2. etc., are connected in three groups of four coils each, the coils cl2, al, a?, and a?, forming one group, the coils a, as, a", and a7, the second group, and the other coils a2, a, al", and c, the third group. The coils of each group are connected in series, the leads g1, g2, g2, from one terminal of the coils a2, a2, and a, at one end of each group being connected in star, and one terminal of the coils a, as, and 0,12, at the other end of each group being connected by a lead m1, m2, and m, to a conductor leading to the source of alternating current.

The terminals n?, n2, and n2, for the three groups of coils cl2, c, c2, 03,-0, c5, c", 02,-02, c, c1", c, on the commutating field core C are connected in the same way as the stator coils c1, a2, etc., to the sourceof alternating current used in operating my improved transformer and the terminals for the other end of the groups of coils being connected in star by leads fv, v2, and v2. The terminals for the synchronous motor G also vare connected to the source of alternating current.

The commutating eld serves for commutating purposes only and contributes no additive effect toward securing higher values of commutated direct-current voltages. The commutating and maini fields in this transformer have the proper angular disposition in space, as shown in Figure 6, and the proper relative field strength, vso that a forward or backward lead of the commutating fie-ld does not alter the angular width of the neutral zone.

For convenience and simplicity in operation it is` preferred to connect each set of coils of one phase of the commutating field in series with a proper corresponding set of coils of one phase of the primary or stator winding the core A. By this Seriesstar connection of the commutating and primary or stator coils an exact phase coincidence of the currentsin these same coils may be brought about for all current values with the result that the proper angular lead, either forward or backward, of the commutating field, can readily be secured.

In Figure 6` I have shown diagrammatil cally the circuit connections which-I prefer to use in order to securethe same phase of currents in the primary coils al to ai12 of the main field of Figure 2, and the primary coils C1 to 01" of the commutating field of my transformer.

The three phasesof these two separate and distinct sets of primary coils are shovn connected in series-star fashion, so that the circuits may be traced from the three phase current supply lines O, P, and Q, as fcllowsz-Line 0 through resistance X, terminal mL coils a, al, a2, a3, lead g1, terminal nl, coils c, c1, c2, c", and star lead nl to star connection 100. Line P through resistance Y, terminal M2, coils (t4, ai, a, a?, lead q2 terminal n2. coils 04, c5, c, c?, and star lead 'v2 to star connection 100. Line Q through resistance Z, terminal m3, coils e8, o, al, a, lead g3; terminal n3, coils es, e9, c1", c, and star lead 113 to star connection 100.

It will'thus be seen that each set of coils of one phase of the commutating field is connected in series with a corresponding set of coils of one phase of the primary or' stator windings. Therefore an exact phase coincidence of the currents in these same coils Vis brought about for all current values. The resistances X, Y, and Z, may be of Vany well known construction'and are adapted to take care of the varying demands for current suppliedby the transformer.

It will be understood that I do not Wish to be limited to the specific construction shown since various changes in the construction and arrangement of parts may be made without departing from the spirit of my invention as defined in the appended claims.

1. A transformer comprising a main field having integrated primary and secondary cores, a plurality of coils on said primary and secondary cores, a core having a 'plurality of coils forming a commutating field, said eommutating field being angularly adjustable about the axis of said primary and secondary cores, each group of 'commutating field coils being in series with a corresponding group of the primary or stator coils, a commutator group connected to the coils of vsaid secondary core, and collectors for said commutator group.

2. A transformer comprising a main field having integrated primary and secondary cores,a plurality of coils on said primary and secondary cores, a. core having a plurality of coils forming a commutating field, said field being angularly adjustable about the axis ofesaid primary and secondary cores, each group of commutating field coils andv each corresponding group of the primary or stator coils being connected in series-star fashion so as to obtain the exact phase coincidence and equal current values in the main and commutating primary field coils.

3. AV transformer comprising a main field having integrated primary and secondary cores, a plurality ofcoils on said primary and secondary cores, a core havin a plurality of coils forming a commutating field, said field being angularly adjustable about the axis of said primary and secondary cores, each group of commutating field coils being in series With a corresponding group of the primary or stator coils so as to obtain the exact phase coincidence and equal current values in the main and commutating primary field coils, and the group series of coils being connected in star, a commutator group connected to the group of coils of said secondary core, and collectors for said commutator group.

4. A transformer comprising a main field having integrated primary and secondary cores, a plurality of coils on said primary and secondary cores, a core having a plurality of coils forming a commutating field,

said fields being displaced approxinnitely 9() degrees in phase and said commutating field being angularly adjustable about the axis of said primary and secondary cores, each group of commutating field coils being in series with a corresponding group of the primary or stator coils, and the group series of coils being connected in star, a commu- Vtator group connected to the group of' coils of said secondary core, and collectors for said cominutator roup. i

In testimony whereof I have hereunto set my hand.

ARTHUR F. NESBVIT. 

